The idea is that passengers rushing to catch trains they're about to miss can actually be dangerous -- to themselves, and to each other. So conductors will pull out of the station exactly one minute after their trains' posted departure times. That minute of extra time won't be enough to disconcert passengers too much when they compare it to their own watches or smartphones ... but it is enough, the thinking goes, to buy late-running train-catchers just that liiiiiitle bit of extra time that will make them calm down a bit. Fast clocks make for slower passengers.